One typical type of NAT server (network address translation server) acts as a gateway between a local network and an external network, such as the Internet. This NAT server is a network device that allows one or more machines (e.g., computers) in the local network to share one public or external network address, such as an Internet address. The NAT server maintains a set of unique local or internal network addresses for the machines in the local network. Accordingly, each machine in the local network has a local network address and a public network address. For communication between the local network and the external network, the NAT server translates back and forth between the public network address and the local network addresses for each of the machines. Typically this network address translation is transparent to the individual machines within the local network and so the machines are not aware of the public address used by the NAT server.